Four charges $q, 2q, -4q$ and $2q$ are placed in order at the four corners of a square of side $b$. The net field at the centre of the square is
$\frac{q}{{2\pi {\varepsilon _0}{b^2}}}$ from $+q$ to $-4q$
$\frac{5q}{{2\pi {\varepsilon _0}{b^2}}}$ from $+q$ to $-4q$
$\frac{10q}{{2\pi {\varepsilon _0}{b^2}}}$ from $+q$ to $-4q$
$\frac{20q}{{2\pi {\varepsilon _0}{b^2}}}$ from $+q$ to $-4q$
The magnitude of electric field intensity $E$ is such that, an electron placed in it would experience an electrical force equal to its weight is given by
Mention characteristics of electric field.
In the given figure electric field at center $O$ due to section $AB$ of uniformly charged ring is $\overrightarrow E$. What will be electric field at $O$ due to section $ACB$ ?
A thin semi-circular ring ofradius $r$ has a positive charge $q$ distributed uniformly over it. The net field $\vec E$ at the centre $O$ is
The intensity of the electric field required to keep a water drop of radius ${10^{ - 5}}\, cm$ just suspended in air when charged with one electron is approximately